A sign asking for people not to stand is plastered on a wall across from the Island Clinic Ebola isolation and treatment center in Monrovia, Liberia, Friday Sept. 26, 2014. The outbreak of Ebola has overwhelmed the weak health systems of some of the world’s poorest countries - there aren’t enough doctors and nurses or even clinics to treat the spiraling number of cases.

A couple rides past the Island Clinic Ebola isolation and treatment center in Monrovia, Liberia, Friday Sept. 26, 2014. The outbreak of Ebola has overwhelmed the weak health systems of some of the world’s poorest countries - there aren’t enough doctors and nurses or even clinics to treat the spiraling number of cases.

MONROVIA, Liberia (AP) — Liberia’s chief medical officer is placing herself under quarantine for 21 days after her office assistant died of Ebola.

Bernice Dahn, a deputy health minister who has represented Liberia at regional conferences intended to combat the ongoing epidemic, told The Associated Press on Saturday that she did not have any Ebola symptoms but wanted to ensure she was not infected.

The World Health Organization says 21 days is the maximum incubation period for Ebola, which has killed more than 3,000 people across West Africa and is hitting Liberia especially hard. WHO figures released Friday said 150 people died in the country in just two days.

Liberia’s government has asked people to keep themselves isolated for 21 days if they think they have been exposed. The unprecedented scale of the outbreak, however, has made it difficult to trace the contacts of victims and quarantine those who might be at risk.

“Of course we made the rule, so I am home for 21 days,” Dahn said Saturday. “I did it on my own. I told my office staff to stay at home for the 21 days. That’s what we need to do.”

Health officials, especially front-line doctors and nurses, are particularly vulnerable to Ebola, which is spread via the bodily fluids of infected patients. Earlier this month, WHO said more than 300 health workers had contracted Ebola in Guinea, Liberia and Sierra Leone, the three most-affected countries. Nearly half of them had died.

Making sure health care workers have the necessary supplies, including personal protective equipment, has been a challenge especially given that many flights in and out of Ebola-affected countries have been canceled.

At an emergency meeting of the African Union on Sept. 8, regional travel hub Senegal said it was planning to open a “humanitarian corridor” to affected countries.

Senegal was expected on Saturday to receive a flight carrying humanitarian staff from Guinea — the first time aid workers from one of the three most-affected countries were allowed in Senegal since the corridor was opened, said Alexis Masciarelli, spokesman for the World Food Program.

The airport in Dakar, Senegal’s capital, has set up a terminal specifically for humanitarian flights where thorough health checks will be conducted, Masciarelli said.

The current plan calls for two weekly rotations between Dakar and Ebola-affected countries and a third weekly rotation between Dakar and Accra, Ghana, where a special U.N. mission to fight Ebola will be headquartered, Masciarelli said.

Mustapha Sidiki Kaloko, African Union commissioner for social affairs, said Saturday he plans to travel to West Africa Sunday to meet regional leaders and airline executives to try to convince them to resume flights canceled because of Ebola.

The first batch of an AU Ebola taskforce, totaling 30 people, left for Liberia on Sept. 18, Kaloko said. Taskforce members are expected to arrive in Sierra Leone on Oct. 5 and in Guinea by the end of October, he said.